This invention relates to an improved knife holder in a woodworking machine such as, but not limited to, a log slabbing chipper or edger.
The present knife holder is an improvement over that illustrated and described in my prior U.S. Pat. No. 3,777,793. The single tightening screw in said patent does not always pull the clamp plate into the holder in a manner which will maintain its proper position against the knife. This often permits the knife to work loose resulting in a poor board surface and wood buildup between the knife and clamp plate. This condition is most pronounced after the part has been in service and has developed minor distortion resulting from stress relief. The only cure for this problem is removal and resetting of the adjusting wedges, which is a relatively tedious procedure requiring welding. This procedure is required also when the clamp plates are replaced because of wear or damage.
Because of the relatively shallow taper in the adjusting wedges, unusual impact on the nosing of the clamp plate will drive it into the holder so tightly that it is difficult to loosen for removal of the knife.
Also, the backing bar assembly in said prior patent does not provide for setting the knife quickly. The knife, clamp plate and backing bar assembly must be removed in order to add or replace special shims for making this setting.